This is how I did it today. I split the clock and the audio so it doesn't get so garbled in the chain. Only mono though, so that's the drawback. That's why I ran the sub in stereo. Guess I could get stereo Y cables and that would fix it.

I often use an iRig 2 to capture a line input to record with my iPhone. Paired with Video Pro for iOS you can monitor the audio being recorded on your device. Alternatively you can listen via the iRig amplifier output without Video Pro.

Here is an example video made with only my pocket devices and the iRig, no mixer or powered amplifier.